Assessing the Validity of Bioelectrical Impedance and Skinfold Calipers for Measuring Body Composition in NOLS Backcountry Hikers

Introduction-The National Outdoor Leadership School (NOLS) conducts backcountry research in an effort to provide the most up-to-date support to its students. Past research efforts have used a variety of body composition measurement tools, including bioelectrical impedance (BIA), skinfold calipers, and air displacement plethysmography (Bod Pod), but these tools are not interchangeable. The purpose of this study was to determine the feasibility and accuracy of the Tanita scale and the Harpenden skinfold calipers for assessing body composition in backcountry hikers. Methods-Twenty-two NOLS participants completed a 23-d backpacking trip into the Wind River Range in Wyoming. Pre- and postexpedition anthropometric measures were collected using 3 different body composition measurement tools: Tanita segmental body composition monitor, Harpenden skinfold calipers, and the Bod Pod. For the purposes of this study, the Bod Pod was used as the standard against which other methods were compared. Results-Participants lost a significant amount of weight and fat during the expedition. Fat-free mass increased by 0.4 +/- 1.9 kg, but this did not reach significance. A high degree of reliability was found between skinfold calipers and the Bod Pod and between BIA and the Bod Pod. The BIA measurements significantly underreported body fat percentage when compared to the Bod Pod, whereas the skinfold measurements were not significantly different from the Bod Pod, but measurements were more variable. Conclusions-This study shows that the skinfold caliper and the Tanita scale give measurements comparable to the less readily available and more costly Bod Pod measurement in backcountry expedition participants.